The similarities are really striking: the size of the amethysts and their shape, even the high pavilions visible on at least two stones in the picture, the structure of the chain - everything but the lenght seem to match the necklace worn by the Duchess of Cornwall. The heart shaped stone seems possibly a bit smaller in your picture only due to the flat angle. I'm sure you and Laurence and Boris are right and she was wearing an altered version of Queen Alexandra's wedding gift. Thanks for the picture!
--Previous Message-- : I´m not quite certain, but I believe the : Duchess of Cornwall is actually wearing a : new version of the necklace gifted in 1923. : There are many similarities. The one thing : that does not fit is the heart-shaped : amethyst. Camilla´s version looks bigger, : and the diamond setting more modern. : : : Described by Fields: : : The necklace was a wedding gift from Queen : Alexandra to Queen Elizabeth the Queen : Mother in 1923 and was given to the Queen : after her marriage. Shortened and redesigned : since 1923, the necklace now consists of : three rows of small pearls interspersed with : eight large oval amethysts, each surrounded : by brilliant-cut diamonds. Hanging from the : front largest cluster is a heart-shaped : amethyst pendant surrounded by brilliants, : and from the four side clusters hang oval : amethyst drops surrounded by brilliants. : : Picture from The Times in 1923: